Lathe for cutting forms.



F. M, ROSS.

LATHE FOR CUTTING FORMS.

'AIPPLICATION FILED DEC. 10, 1914.

1,162,255. Patented Nov. 30, 1915.

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F. M. ROSS.

LATHE FOR CUTTING FORMS.

APPLICATION FILED 050.10, 1914.

1,162,255. Patented Nov. 30, 1915.

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APPLICATION FILED DEC. 10, I914,

1 1 62,255.- Patented Nov. 30,1915.

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FREDERICK M. ROSS, OF CINCINNATI, OHIO.

LATHE FOR CUTTING FORMS,

Specification of Letters Patent.

Application filed December 10, 1914. Serial No. 876,544.

To all whom it may concern:

Be it known that I, Fnnnnnron M. Ross, a citizen of the United States of America, and resident of Cincinnati, county of Hamilton, and State of Ohio, have invented certain new and useful Improvements in Lathes for Cutting Forms, of which the following is a specification.

My invention relates to a lathe for cutting forms, such as lasts, from blocks of wood or other material. to make them conform to the shape of a model or master last.

I-Ieretofore it has been customary to re move the major part of the surplus wood of the block to make it approximate the shape of the model, by a roughing operation and then to remove the balance of the surplus, to bring the block to conform to the model, by a finishing operation. The roughing operation has been performed either by a separate cutter moving in advance of the finishing cutter, or by a cutter which had a forward portion, which performed the roughing operation, and a rearward portion, which performed the finishing operation. In either instance, the bulk and shape of the cutter limited the speed at which it could be run and rendered it incapable of cutting the sharp curves that are found necessary in modern last, thus necessitating trimming the lasts by hand to obtain these curves.

In lathes of this character it has been customary to actuate the spindle of the cutter by a belt, which has sliding connection with an enlarged drpm upon a driving shaft. This driving means had limitations as to speed. The means too of mounting knivesupon the cutter heads has been such, that too great a strain was placed upon the knives, if the heads were rotated beyond a certain rate of speed.

The object'of my invention is a lathe,

which will perform rapidly and in one operation, and by one cutter head, the work that has heretofore been accomplished by r the roughing and finishing operations of one or more cutter heads in last lathes and simi-' lar lathes. I attain this object by means of a cutter head, which is spheroidal in shape,

, mechanism, which imparts high speed of revolution to the cutter head.

Referring to the drawings: Figure 1 is a front elevation of a last lathe of ordinary construction, showing my invention inconnection therewith. Fig. 2 is a plan view of the lathe bed with the apparatus embodying my invention attached thereto: Fig. 3 is a side elevation of the apparatus embodying my invention detached from the lathe. Fig. at is an end view of a cutter head forminga Patented Nov. 30,1915.

portion of my improved apparatus. Fig. 5 I

is a sectional view of the cutter head illustrated in Fig. 4 and taken on line 55 of Fig. 4e. Fig. 6 is a view illustrating the parts of my. improved cutter head, expanded to the position they oceupyin properly locating the knives, and also to more fully disclose the construction thereof. Fig. 7 is a view of a knife employed in my cutter head. Figs. 8 and 9 are respective end and side ele vations of a modified form of cutter head embodying my invention. Fig. 10 is a fragmental sectional view of a screw-threaded socket, into which the cutter head en1bodying my invention is adapted to be screwed, in locating it properly on the lathe. Fig. 11 is an elevation of the head shown in Fig. 4:. Fig. 12 is a longitudinal section of the bearings of the worm. Fig. 13 is a perspective view of the cutter head.

I have illustrated my invention as applied toa well-known type of last turning machine, which I will describe first. This last turning machine comprises a bed portion 1 7 supported upon legs 2 and from which project upright standards 3 connected one with the other and suitably braced to form a rigid, main frame. Pivotally supported upon forward extending arms 4, car ried by the upright standard 3, is a swingingframe comprising pendant arms 5 connected by transverse bars 6 and suitably braced into a rigid structure, which is free to oscillate forward and rearward about its pivotal connection 7. Carried upon suitable trunnions, journaled in bearing bars 8, is the revoluble master form 9.- The drive trunnion of the master form, carries a gear pinion 10, -meshing with a corresponding pinion 11, upon a counter shaft 12. This counter shaft 12 carries a second pinion 13 meshing with a corresponding pinion 14:,

upon the drive spindle or trunnion 15, whichcarries at its extremity a pulley 17, connected by a belt 18 with a counter shaft 19, operatively connected through sundry belts and counter shafts with the main drive shaft 20 journaled in the lower part of the main frame. By the rotation of the main drive shaft 20, the counter shaft 12 is rotated to revolve the master form 9 and the work 16 in unison. This revoluble movement of the master form and work continues at a uniform rate, regardless of the oscillatory movement of the swinging frame.

Slidingly mounted to reciprocate upon the bed 1, is a carriage 21, carrying a master or guide wheel 22, engaging the master form 9, and a second carriage 28, carrying a cutter head of my invention, and which operates uponthe work 16, journaled in the swinging frame and rotated by the counter shaft 12. These carriages 21 .and 28 move in unison under the influence of feed de vices 2a.

The swinging frame at all times tends to move inward, which movement is arrested by the engagement of the master form 9 with the guide or master wheel 22. As the master form 9 is rotated, the portions thereof at greater or less distance from the axis, brought into engagement with the master or guide wheel, causes the swinging frame to oscillate to shift the work 16 to or from the cutter head, causing said cutter head to operate'at greater or less depth in the last block or rough stock.

The sliding movement of the heads 21 and 23, causes the master wheel 22 to successively engage every portion of the master form 9, the cutter head being moved'in unison with the master or guide wheel'22, is caused to operate upon every portion of the block or rough stock, whereby there is produced a finished product which is the counter part of the master form 9. This is the usual construction and operation of turning machines of this type, and in itself forms no part of the present invention.

The cutter head embodying my invention is the shape of an oblate spheroid and is formed preferably of two interlocking blocks A and B. Block A is elliptical in longitudinal cross-section and has sides a a, which diverge away from the stem Z) of the outer head. In the block A is formed a transverse groove, whose walls a a converge toward the pole from which projects the stem Z). Block B is split in half though the aXis of the stem 6. The body of this block is the converse of the block A, that is, it is spheroidal in transverse cross-section, has a longitudinal groove, whose walls I) b are diverged upwardly from the. stem 6, and whose. sides b b converge upwardly toward -,..the stem. The sides a a and-thewalls b b are at the same anglev to the stem 6;, and-the wallet, a and the sides 6? b are. at thesame angle to the stem 6. Hence there is left between the walls b a and a 6 slots which diverge upwardly from the stem Z), and be tween the walls a a and the sides 6 1) slots which converge upwardly toward the stem 6. These slots form seats for the knives D D D D The means for adjusting the knives in their seats and for clamping them therein, are as follows: Block A has an axial internally screw-threaded perforation a", in which is seated a set screw E, the inner end of which is concaved to form a circular ridge 6. Upon the end of each member of the split block B, there is formed in alinement with the cylindrical stem a semi-circular groove 6 b which stands in alinement with the ridge 6, when the halves of the block have been brought together. By tightening the screw E against the block B, knives in the ways will be clamped between the blocks A and B. A coiled spring E surrounds the inner end of the screw E and holds the blocks A and B yieldingly together, when the screw is loosened, to permit adjustment of the knives.

In Fig. 9 is illustrated a modification of the cutter head. This cutter head B is like cutter head B in the form of an oblate spheroid. It differs from the cutter head heretofore described, in that it is integral. It has parallel grooves 5 11 which diverge upwardly from the stem b, and at right angles to this set of grooves a second set of parallel grooves Z) are converged upwardly toward the stem 6 The external walls of the head have screw threaded perforations for the reception of set screws 5, by which the knives are locked in the head, after having been adjusted.

There are four knives C, the cutting edges 0 of which are approximately semi-elliptical. When the knives are secured in their grooves, the cutting edges of the knives in the divergent grooves overlap the path of the cutting edges of the knives in convergent ones. lVhen clamped in place the walls of the cutter head contacts with the entire knife, except a narrow portion adjacent to the cutting edge.

The half stems b have external screw threads, which engage a screw threaded socket f in the end of the spindle F. Spindle F is journaled in a longitudinal bore f in bearing block 7, which is mounted adjustably upon an angle plate F, which is mounted adjustably upon the carriage 23. The means for mounting the bearing block 7 adjustably upon angle plate F are horizontal pins f 7, which project from the bearing block f into vertical slots f f in the angle plate. The ends of the pins f f are screw threaded for the reception of nuts 7" 7, for clamping thebearin block to the angle plate, after the proper adjustment has been secured. The means for adjusting the angle plate F upon the carriage are vertical pins 24 24 projecting upwardly from the carriage, through slots 7 j in the angle plate, and nuts f f engaging the ends of the pins. Spindle F is connected by a universal joint F to an actuating shaft G, which is splined in a worm G. Worm G is mounted in a longitudinal recess in, in the top of gear box H. The screw of the worm is left handed.

lVithin the recess are bushings h, if, upon which ends 9 g of the worm bear. Between the inner ends of the bushings and the worm are ball thrust bearings h h A bearing disk G is journaled in a bracket 9 secured to the bear box, and bears against the end 9 of the worm, to relieve the ball bearings of the end thrust of the worm. Rotation is imparted to the worm G by a large worm wheel K, which is secured upon shaft 77, which carries at one of its ends a fast pulley 7c and a loose pulley 70 which are connected by a belt 70 to a pullety 20' on the end of the driving shaft 20. The shaft Gr is braced by passing through a bearing block G which is secured to an extension 23 of the carriage 23.

In operation: Spindle F of the cutter 7 head is adjusted by means of universal joint F the adjustable bearing block f and the angle plate F so that its axis is parallel to the axis of the guide wheel 22. By the universal joint F, a great variety of adjustments of spindle F may be had, to fit it for any shape of last. After the guide wheel 22 has been brought into contact with the model M, and the cutter head has been brought adjacent to the work W, the belt k is shifted to the fast pulley la. Worm wheel K then imparts a high speed of rotation to the worm G, which in turn imparts said rotation to the shafts G and cutter head. As the carriage 23 is reciprocated in the usual manner, the cutter A is fed longitudinally along the work. This longitudinal movement of the cutter is permitted by the shafts G sliding through the worm G, because of its being splined therein. Worm G being left handed, its thrust against the screw threads of pinion K tends to move the worm rearward. The friction between the spline of shaft G and the worm tends to draw the worm forward, hence this friction counteracts the thrust of the worm.

The spheroidal contour of the cutter head enables it to trace accurately all the curves of the model M, for the reason that it has no projecting shoulders or corners to contact withthe work. The cutting edges of the knives being semi-elliptical, conform to the shape of the cutter head, so that the knives project uniformly beyond it. Both faces of the knives being clamped between the walls of the cutter head, except for the narrow portion which projects beyond the cutter head, the strain of the cutting action on the knives is reduced to a minimum, so that, though the knives be very keen, they may be run at a very high rate of speed. This strain of the cutting action likewise is reduced, because the character of the cut made by the knives is a shaving or draw out.

The type of the cut combined with the speed of rotation and the shape of the cutter head, enables my cutter to reproduce a smooth last, like the model, in one operation.

What I claim is:

1. In a machine of the character described, the combination of a rounded cutter head, knives mounted in the cutter head, whose cutting edges project slightly beyond and conform to the contour of the cutter head, a reciprocable spindle for the cutter head, a worm, a shaft splined in the worm and connected to the spindle, and a driving pinion engaging the worm.

2. In a machine of the character described, the combination of a rounded cutter head, knives mounted in the cutter head, the edges of the knives projecting slightly beyond andconforming to the contour of the cutter head, a reciprocating carriage, a spindle for the cutter head, means for mounting the spindle adjustably upon the carriage, a worm, a shaft splined in the worm and coupled to the spindle, and a driving pinion engaging the worm.

3. In a machine of the character described, the combination of a spheroidal cutter head, two sets of parallel grooves formed in the cutter head, one set of said grooves being at right angles to the other set, and one set thereof being at an angle divergent from the stem of the cutter head and the other set being convergent toward said stem,

a stem upon the cutter head connecting it to FREDERICK M. ROSS.

Witnesses:

WALTER F. MURRAY, W. THORNTON Boenn'r.

Copies of this patent may be obtained for five cents each, by, addressing the Commissioner of Batents, Washington, D. G. 

